1. Field of the invention:
This invention relates to an electrochemical detection device that electrochemically measures specific substances in a test solution. More particular, this invention relates to an electrochemical detection device in which the working electrode can be readily installed in and from which the working electrode can be readily removed by a simple operation.
2. Description of the prior art:
Electrochemical detection devices have a cell through which a test solution can pass, and a working electrode and a counter electrode that apply a given voltage to the test solution within the said cell. The working electrode and counter electrode apply voltage to the test solution within the cell, resulting in an electrochemical reaction by which the amount of specific substance in the test solution is measured. Ordinarily, the cell mentioned above is formed of a cell block. Each of the electrodes is formed so as to have a given shape and size, and they are introduced into said cell block and fixed by means of a screw or the like. The electrodes are connected electrically to measuring devices on the outside.
These kinds of electrochemical detection devices have been used in recent years to assay the amounts of catecholamines or other kinds of biochemicals in test samples. Test solutions that contain such kinds of biochemicals state the electrodes and the cell wall. In particular, the working electrode is readily stained by test solutions. Staining of the inside of the cell and of the electrodes decreases the accuracy of the measurements. For this reason, it is necessary to clean the inside of the cell and the electrodes. The inside of the cell is cleaned by the opening of the cell. Conventional cells are made into the one unit by the screwing together, etc., of elements of the structure of the cell. For this reason, in order to open the cell, the structural elements of the cell must be taken apart, and after the inside of the cell has been cleaned, it is necessary to reassemble the structural elements, which requires a great deal of work.
When the electrodes, also, are to be cleaned, it is necessary that the electrodes be released from the cell block. Also, when the sample to be assayed in an electrochemical detection devices is changed, it is necessary to replace the electrodes with different ones. In this circumstance, too, the electrodes that are fixed with screws or the like to the cell block must be temporarily removed from the cell block. When the electrodes are being exchanged, first the electrical connections between the electrodes and the fixed measurement devices must be removed, and then different electrodes must be fixed to the measurement devices, after which it is necessary to restore the electrical connections between the new electrodes and the fixed measurement devices. In this way, the cleaning or replacement of electrodes requires the carrying out of a very complex process.
Moreover, electrochemical detection devices sometimes give rise to bubbles in the test solution that remain in the solution as the solution flows through the cell. The bubble that remain in the test solution are deformed elastically when pressure is applied to the test solution. These elastic deformations of the bubbles give rise to noise at the time of measurement, and measurements cannot be made with accuracy.